Integrity error in pytest Flask-SQLAlchemy session

Question

I'm porting the tests of a Flask application from unittest to pytest. For tests that need a database I added a fixture that returns a DB session

The DB is an SQLAlchemy object that runs a PostgreSQL database

import pytest
from app import create_app, db
from app.models import Project, Client

@pytest.fixture(scope='function')
def db_session():
    app = create_app('testing')

    app_context = app.app_context()
    app_context.push()

    db.create_all()

    yield db.session

    db.session.remove()
    db.drop_all()
    app_context.pop()

def test_getJson_withOneProjectSet_returnsBasicClientJson(db_session):
    testClient = Client()
    db_session.add(testClient)

    testProject = Project()
    db_session.add(testProject)

    testClient.projects.append(testProject)

    db_session.commit()

    clientJson = testClient.getJson()

    assert len(clientJson['projects']) == 1


def test_getJson_withThreeProjectsSet_returnsBasicClientJson(db_session):
    testClient = Client()
    db_session.add(testClient)

    testProject1 = Project()
    db_session.add(testProject1)

    testProject2 = Project()
    db_session.add(testProject2)

    testProject3 = Project()
    db_session.add(testProject3)

    testClient.projects.append(testProject1)
    testClient.projects.append(testProject2)
    testClient.projects.append(testProject3)

    db_session.commit()

    clientJson = testClient.getJson()

    assert len(clientJson['projects']) == 3

When running the tests, the first one passes but the second one returns an integrity error: sqlalchemy.exc.IntegrityError: (psycopg2.IntegrityError) duplicate key value violates unique constraint "project_code_key"

Apparently the DB is not cleaned up after finishing a test-function

The fixture is a port from a working unittest setup/teardown function that has no problems with integrity errors:

# def setUp(self):
#     self.app = create_app('testing')
#     self.app_context = self.app.app_context()
#     self.app_context.push()
#     db.create_all()
#
# def tearDown(self):
#     db.session.remove()
#     db.drop_all()
#     self.app_context.pop()

alim91 alim91 · Accepted Answer · 2020-10-05T12:42:40

try put scope="module" instead of function, scope module means use this db for all tests then drop it

Integrity error in pytest Flask-SQLAlchemy session

1 Answers